The friendship between Harigtay and Swift has been growing for a while now. The TV actress noted in May that she and the pop star had originally met at the Met Gala, then ran into each other at a concert. Hargitay next had a brief cameo in Swift's music video, "Bad Blood."

This time, Hargitay was in Philadelphia for Swift's show, and even came out on stage during "Style." The historic Olivia/Olivia meeting happened backstage.